package 强化训练;

import java.util.Scanner;
//********自己测试没问题，牛客通过0
public class day33斐波那契数列求和 {
    public static void main(String[] args){
        long[] res = new long[81];
        res[1] = 1;
        res[2] = 1;
        long sum = 2;
        for (int i = 3; i < 81; i++) {
            res[i] = sum + res[i-1] + res[i - 2];//缓存前i项的和
            sum = res[i];
        }
        Scanner sc = new Scanner(System.in);
        while(sc.hasNext()){
            int sta = sc.nextInt();
            int end = sc.nextInt();
            long ret = res[end] - res[sta];
            System.out.println(ret);
        }
    }
}
